Medical procedures are available for treatment of a variety of cardiovascular maladies, such as cardiac arrhythmias, atrial fibrillation, and other irregularities in the transmission of electrical impulses through the heart. As an alternative to open-heart surgery, many medical procedures are performed using minimally invasive surgical techniques, where one or more slender implements are inserted through one or more small incisions into a patient's body. Such procedures may involve the use of catheters or probes having multiple sensors, electrodes, or other measurement and treatment components to treat the diseased area of the heart, vasculature, or other tissue. Minimally-invasive devices are desirable for various medical and surgical applications because they allow for shorter patient recovery times compared to surgery, and for precise treatment of localized discrete tissues that are otherwise difficult to access. For example, catheters may be easily inserted and navigated through the blood vessels and arteries, allowing non-invasive access to areas of the body with relatively little trauma, while other minimally-invasive probes or instruments may be inserted into small openings and directed through targeted anatomy without significant impact or disruption to surrounding tissue.
One such example of a minimally invasive therapy involves the treatment of cardiac arrhythmias or irregular heartbeats in which physicians employ specialized cardiac assessment and treatment devices, such as a mapping and/or ablation catheter, to gain access to interior regions of a patient's body. Such devices may include tip electrodes or other ablating elements to create lesions or other anatomical effects that disrupt or block electrical pathways through the targeted tissue. In the treatment of cardiac arrhythmias, a specific area of cardiac tissue having aberrant electrical activity (e.g. focal trigger, slow conduction, excessively rapid repolarization, fractionated electrogram, etc.) is typically identified first before subsequent treatment. This localization or identification can include obtaining monophasic action potential (“MAP”) electrograms of a particular cardiac region. Monophasic action potentials reproduce complete action potential of cardiac tissues including the repolarization time course of myocardial cells with high accuracy and provide precise information on local activation. MAP signals may be obtained by temporarily depolarizing selected tissue, with responsive electrical activity being recorded or otherwise monitored for an indication of aberrant electrical activity. After mapping and diagnosing aberrant tissue, a physician may decide to treat the patient by ablating the tissue.
Recording MAP signals and subsequently treating affected areas involve maneuvering selected diagnostic and treatment devices through restricted and sometimes tortuous pathways to access the desired tissue region. The restrictive environment surrounding the targeted tissue can reduce the ability of a device to be properly positioned to obtain the desired information and/or deliver the treatment needed. To provide more effective and efficient medical treatments, it is thus desirable to optimize the apparatus and method of use for the specific tissue to be treated, taking into account the characteristics of the tissue to be diagnosed and treated, as well as the location and pathway of access to the selected tissue.